The present invention relates to an information recording/reproducing apparatus using an information recording medium capable of recording information by irradiation with optical beams, and more particularly to an information recording apparatus for improving an error rate to a phase change optical disk.
As a conventional rewritable optical disk, there is known a DVD-RAM realizing a storage capacity of 2.6 GB on a single side of a disk having a diameter of 120 mm made of a phase change material.
In JP-A-10-320777, there is disclosed a write parameter calibration technology for optimizing recording power since there is a need for executing a precise formation of a recorded mark for a large capacity optical disk such as a DVD-RAM.
The conventional write parameter calibration comprises the following processes:
(1) Process of recording a test pattern on a disk while changing recording power.
(2) Process of detecting a phase difference between a data edge and a clock edge at reproduction and acquiring optimum recording power by determining threshold power of recording in which a phase difference is equal to or lower than a given value and multiplying it by a constant.
With these processes, the recording power can be acquired with accuracy of about xc2x13% of the optimum condition.
Referring to FIG. 2, there is shown a recording strategy used for a 2.6 GB DVD-RAM. To further increase a recording capacity of a rewritable optical disk, it is indispensable to write a recorded mark having a half or smaller size of an optical spot more precisely. To form a fine mark very precisely in this manner, a medium need be irradiated with beams while changing power or a pulse width adaptively according to data patterns preceded or followed by the recorded mark as well as using optical pulses synchronized with clocks as shown in FIG. 2. For example, to change width W of a pulse string adaptively as a recording condition, W=W (xe2x80x94, a previous space length, the mark length, a subsequent space length, xe2x80x94).
Referring to FIG. 3, there is shown the write parameter calibration method disclosed in JP-A-10-320777 as a conventional art. In the conventional write parameter calibration method, the recording power has been determined by evaluating a phase difference between data and a clock as an error count while changing the recording power. In the conventional one, it was impossible to determine a recording condition of power or a pulse width according to previous and subsequent data patterns as set forth in the above.
It is an object of the present invention to provide an optical disk drive for further increasing a recording capacity of an optical disk, specifically to provide a write parameter calibration method used prior to actual recording of information to realize of a large amount of recording. Particularly, it is an object of the present invention to provide a write parameter calibration method for realizing an improvement of power determination accuracy and an optimization of the recording condition depending on previous and subsequent data patterns and an optical disk drive using the method.
To resolve the above problem, the following write parameter calibration method and an optical disk drive using it are used.
(1) Write parameter calibration method, comprising:
a process of recording data patterns on an information medium while controlling a recording condition according to the recording data patterns;
a process of reading the data patterns recorded on the information medium to acquire a reproduced signal;
a process of detecting a phase difference between the reproduced signal and a reference signal;
a process of discriminating the phase difference for classification according to the data patterns; and
a process of determining the recording condition according to the discriminated phase difference.
(2) Write parameter calibration method, comprising:
a process of recording the data patterns on an information medium while controlling the recording condition according to recording data patterns;
a process of reading the data patterns recorded on the information medium to acquire a reproduced signal;
a process of measuring the number of marks or of spaces included in the reproduced signal;
a process of comparing the number of marks or of spaces in the reproduced data with the number of marks or of spaces in the recorded data; and
a process of determining the recording condition according to a result of the comparison.
(3) Write parameter calibration method according to (1) or (2) in the above,
wherein the information medium is a disk-type optical information recording medium;
wherein the reference signal is a clock signal generated from the reproduced signal; and
wherein the recording condition is power, a pulse width, or a position of an emitted laser beam.
(4) An optical disk drive, which is an information device for recording and reproducing information on an optical information recording medium, at least comprising:
means for rotating the optical information recording medium;
means for condensing semiconductor laser beams into the optical information recording medium; and
laser driving means for modulating an output, a pulse width, or a position of the semiconductor laser according to the recorded data,
wherein it has a function of determining a condition for recording into the optical information recording medium using the write parameter calibration method according to (1), (2), or (3).
(5) An optical disk drive according to the above (4), further comprising:
means for recording the recording condition determined by the write parameter calibration into a specific area of the optical information recording medium; and
means for reproducing the recording condition recorded on the optical information recording medium.
The present invention is also applicable to a write-once optical disk of an optical magnetic disk type or of a perforation type as well as the phase change optical disk.